Segmented polyurethanes containing monodisperse hard segments



United States Patent 01 ice 3,541,053 Patented Nov. 17, 1970 ABSTRACT OFTHE DISCLOSURE Segmented polyurethanes containing monodisperse hardsegments derived from low molecular weight diols and diamines and softsegments derived from polyether glycols. The hard and soft segments areconnected bp urethane linkages. The segmented polyurethanes are usefulas fibers and in making cast objects.

BACKGROUND OF THE INVENTION In the art of forming polymers based onurethane linkages, two routes to the urethane structure are well known,i.e., reaction of an isocyanato group with a hydroxyl group, andreaction of a chloroformate group with a primary or secondary amine,with elimination of the elements of hydrogen chloride. The presentinvention is based on the latter route.

It is generally found that reaction of the bis-chloro formate of any ofthe relatively simple low molecular weight diols with a primary orsecondary diamine in the presence of an acid acceptor such as sodiumcarbonate will yield a linear, crystalline polymer having a relativelyhigh melting temperature, usually greater than 150 C. and often 30 C. orhigher. High-melting, crystalline polyurethanes of this sort areillustrated in US. Pat. No. 2,973,333 and 3,089,864, to Katz andWittbecker.

The strong tendency of polyurethane chains of the sort described by Katzand Wittebecker to associate in a crystalline configuration makes suchpolymers hard, almost intractable materials. Katz took advantage of theassociative tendencies of such hard polymer structures in the inventionof his US. Pat. 2,929,802 by building into an inherently softpolyalkylene based on relatively high molecular weight polyalkyleneether diols randomly placed hard segments of the above-described type.The resulting polymers consisted of randomly alternating hard and softsegments, each type occurring in a range of segment sizes, because theyresulted from the simultaneous reaction of a diamine, a low molecularweight glycol bischloroformate, and a high molecular weight polyalkyleneether glycol bis-chloroformate. The associative tendency of the hardsegments is suflicient to give the effect of crosslinks between chains,such that the resulting polymers have valuable elastomeric properties infiber form.

The hard segments of the prior art segmented polyurethanes are randomlydistributed and are of varying length, deepnding on the statisticalchance of reaction of diamine with low or high molecular weightbis-chloroformate. The associative tendency of such hard segments istherefore uncontrolled and inefiiciently used, which to some extentadversely affects the physical properties of the polymer. Such polymerscan be described as containing polydisperse hard segments.

SUMMARY OF THE INVENTION This invention provides segmented ployurethanescomprised essentially of soft segments and monodisperse hard segments ofcontrolled size and distribution, said polyurethanes comprisingessentially repeating units of the formula wherein G is a bivalentradical obtained by removing the hydroxyl hydrogen atoms from apolyalkyleneether glycol having a molecular weight greater than 400 anda melting point less than 50 C., B is a bivalent radical obtained byremoving the hyrdoxyl hydrogen atoms from a diol having a molecularweight less than 400, A is a bivalent radical obtained by removing ahydrogen atom from each amino group of an organic diamine, and n is aninteger of 2-12.

DETAILED DESCRIPTION The polymers of this invention are composed of twosegments: hard segments derived from diamines and low molecular weightdiols bonded together through urethane linkages,

o Jail-oand soft segments derived from polyalkyleneether glycols. Thesoft and hard segments are also connected through urethane linkages. Thearrangement of the hard and soft segments in the polymer chain cantherefore be represented as follows:

Soft Segment Hard Segment wherein G, A, B and n are as defined above.The end groups of the polymer are amines or hydroxyls, the latterresulting from hydrolysis of the chloroformate group. The presence ofthe above-described segments and the connecting urethane linkages isevident from the known chemistry of the reactants used, infraredspectroscopy and melting point studies of the polymers.

The hard segments of the subject polymers are high melting crystallinemoieties prepared by reacting the haloformate of a low molecular weightdiol with a primary or secondary diamine. They consist of at least 2repeating units of the formula:

Preferably, they are sufiiciently high melting that a high molecularweight homopolymer of these repeating units in the fiber-formingmolecular weight range (about 5000 or higher), would melt at C. orhigher. However, less crystalline, lower-melting hard segments can alsobe used. The melting point and crystallinity of the hard segmentsdepends on the low molecular weight diols and diamines used and the sizeof the hard segment (value of n), as will be discussed later.

The soft segments of the polymers are the residues remaining afterremoval of hydroxyl hydrogens from polyalkyleneether glycols having amolecular weight above 400 (preferably between 600 and 5000). Suchpolyethers melt below about 50 C.

A critical feature of the polymers of this invention is that the hardsegments are monodisperse, which means the size of the hard segment ineach repeating unit of the polymers, as described in the formulae givenabove, is the same. The value of n is therefore constante throughout anyquantity of polymer within the scope of this invention.

The polymers of this invention are prepared by preforming the hardsegment to a predetermined size and reacting the resulting material withthe bis-chloroformate of a polyalkyleneether glycol. In preparing thepreformed hard segment from the diamine and diol, it is necessary toblock one end of one of the difunctional reactants with a protectivegroup such as benzylchloroformate in order to control the size of thesegment as it is formed. A representative preparation of the hardsegment wherein is phenyl and X and Y are the same as A and B,respectively, defined above, without the amine nitrogens and dioloxygens, is given below (the amine exemplified is a secondary diamine):

Compound VI is typical of the smallest hard segments which can bereacted with a polyalkyleneether glycol to prepare segmented polymerswithin the scope of this invention. Those skilled in the art willrecognize that higher molecular weight hard segments in which n is aneven number can be prepared by reacting compound VI with 2 moles ofcompound IV, treating the resulting material (wherein n=4) with hydrogenand palladium catalyst and, if desired, continuing to react theresulting aminoterminated hard segments with compound IV and removingthe blocking groups until the desired value of n is obtained. Hardsegments in which n is 3 or a higher odd number are prepared by formingcompound I as indicated above and proceeding as follows:

Hard segments of higher molecular weight in which n is an odd number areprepared by reacting compound X with compound IV, treating the resultingpolymer with hydrogen and palladium catalyst and continuing to react theresulting amino-terminated hard segment with compound IV and removingthe blocking groups until the desired value of n is obtained.

The segmented polymers of this invention are prepared by reacting one ofthe hard segments described above with the bis-chloroformate of apolyalkyleneether glycol as illustrated by the following representativereaction:

wherein n is constant throughout the polymer, Z is the same as G,defined above, without hydroxyl oxygens, and the end groups are aminesor hydroxyls depending on the proportions of reactants used.

The segmented polyurethanes of this invention are unique in that thehard Segments of the polymer are monodisperse. Consequently, thepolymers have greater crystallinity and thus sharper and better definedmelting points than the polydisperse segmented polyurethanes of theprior art. These properties are reflected in a substantial increase inmodulus and tensile strength of the polymers of this invention. Thepolymers of this invention are therefore a special class of the linearpolymers of the prior art which have no cross links but which exhibitproperties equivalent to those of cured, crosslinked elastic products.

The proportion of hard segments to be built into the polymer chaindepends on the use to be made of the polymer. As the proportion of hardsegments increases, the polymers become increasingly crystalline, hardand inflexible to the point they are a hard plastic. Conversely, as thehard segment proportion decreases, the polymer loses its crystallinityand becomes softer and more flexible. At very low hard segment contents,the polymer is a soft elastomer. For use in applications such aselastomeric fibers, coatings, and molded goods, it is preferred that thehard segment be about 10-50% by weight of the total polymer. Thepreferred value of n is about 36 since the resulting polymers have goodphysical properties and can be prepared from readily available startingmaterials.

The diamines used as components for the hard segments can be primary orsecondary aliphatic, alicyclic, aromatic or heterocyclic diamines.Representative diamines include ethylene diamine, propylene diamine,tetramethylene diamine, pentamethylene diamine, hexamethylene diamine,heptamethylene diamine, octamethylene diamine, piperazine,2,5-dimethylpiperazine, p-Xylylene diamine, 1,4-diaminocyclohexane,p-phenylene diamine, bis(paminocyclohexyl)methane, 1,3di(4-piperidinyl)propane and many others. Mixtures of diamines can alsobe used. Derivatives of the diamines can be used so long as thesubstituents do not interfere with the polymerization reactions. Forexample, the aliphatic diamines used can have hydrocarbon side chains orbe substituted with halogens.

The low molecular weight diols used with the diamines to prepare thehard segments include aliphatic, aromatic, mixed aliphatic aromatic orcycloaliphatic diols. Examples include ethylene glycol, propane diols,butane diols, pentane diols, o-, In-, and p-Xylylene glycol, cyclohexanediol, hydroquinone, 2,5-dihydroxydioxane, resorcinol, catechol and4-methyl resorcinol. As with the diamines, mixtures of the diols can beused and the diols can be substituted with groups that do not interferewith the reactions required in preparing intermediates and the ultimatepolymerization reaction.

In general, diamines and diols which form hard segments having meltingpoints of C. or higher at a molecular weight above 5000 should be used.That is, diamines and diols that can be connected through urethanelinkages to form a polymer having a molecular weight greater than 5000which melts at least as high as 150 C. are preferred though otherdiamines and diols can be used.

The symmetrical diols and diamines are preferred since they lead to morecrystalline, higher melting, hard segments. The preferred ultimatesegmented polymers resulting from these symmetrical diols and diamines,therefore, have increased modulus and tensile strength. Preferredsymmetrical diamines include polymethylene diamines of the formula HN{-CH -},,NH wherein n is 2-6, 1,4-cyclohexanediamine,p-phenylenediamine, piperazine, 2,5-dimethylpiperazine, and1,3-di(4-piperidinyl)propane. Piperazine is particularly preferred sinceit readily undergoes polymerization reactions as described above to formhighly crystalline hard segments. Preferred symmetrical diols includealkylene diols of the formula HOtCH -AOH wherein n is 2-6,1,4-cyclohevanediol and hydroquinone. 1,4-butanediol is especiallypreferred because of its availability and the high melting crystallinehard segments which it forms.

The polyalkyleneether glycols which make up the soft segments of thepolymer have molecular weights greater than 400 and preferably fromabout 6005000. They melt below 50 C. Polyalkylene thioethers can also beused. Representative polyethers include the polyoxathioalkylene glycols,such as poly(1-oxa-4-thiahexane), poly(1,4-dioxa- 7-thianonane), andpoly( 1,6-dioxa-9-thiahendecane); the poly(alkyleneether) glycols, suchas poly(ethyleneether) glycol, poly(propyleneether) glycol,poly(tetramethylene ether) glycol, and poly(decamethyleneether) glycol;polydioxolane, and polyformals prepared by reacting formaldehyde withother glycols or mixtures of glycols, such as tetramethylene glycol andpentamethylene glycol. Some of the alkylene radicals in these polyetherscan be replaced with arylene or cycloaliphatic radicals. The preferredpolyether is poly(tetramethyleneether) glycol because of the elastomericcharacter and water resistance of polymers prepared from it.

As indicated above in the descriptions of the preparation of the hardsegments and the reaction of the hard and soft segments, the componentsare not reacted directly. Instead, one component is first converted tothe corresponding haloformate or carbamoyl chloride which is thenreacted with the other component. The haloformates can be the chloro-,bromo-, iodoor fluoroformate, but usually the chloroformates will beemployed since they are easily prepared from phosgene.

The segmented polymers of this invention have an inherent viscositygreater than 0.5 and preferably greater than 2.0. Polymers in the lowermolecular weight range are useful in applications such as thepreparation of molded objects. Polymers of higher molecular weight i.e.,above about 5000 are useful as fibers. Inherent viscosity is defined as:

ln m C wherein 1 is the ivscosity of a dilute solution of the polymerdivided by the viscosity of the solvent in the same units and at thesame temperature, and C is the concentration in grams of the polymer perhundred ml. of solution. The inherent viscosity values given herein arebased on a solution of polymer in m-cresol at 30 C. (0.1 gram in 100 ml.of solution).

The polymers of this invention are useful in making polyurethane fibers,coatings and cast objects, particularly where tough durable polymerswith high modulus and tensile strength are required. The polymers neednot be cured by cross-linking to form a useful product. Procedures wellknown in the art for preparing coatings and cast elastomers fromconventional crosslinked elastomers are applicable here. Because oftheir crystallinity, the polymers of this invention are especiallyuseful in injection molding Where the polymer is heated above itsmelting point and injected into a mold, as the polymer rapidlysolidifies to the desired shape. Because the polymers are readilysoluble in solvents such as methylene chloride,

chloroform, trichloroethylene and mixed solvents such as toluene andethanol, they are well suited for use as lacquers. As fiber-formingmaterials the polymers can be melt, dry, or wet spun by procedures wellknown in the art such as those described for polydisperse hard segmentpolymers in U.S. Pat. 2,929,802 to Katz.

The reaction of the polyether bis-chloroformate and amine-terminatedhard segment can be carried out by interfacial polymerization orsolution polymerization as generally described in columns 7 and 8 ofU.S. Pat. 2,929,- 802 to Katz.

In interfacial polymerization, the solvents are usually water and anorganic solvent in which the polyether bischloroformate and hard segmentare soluble, e.g., methylene chloride, chloroform and trichloroethylene.An acid acceptor soluble in the Water phase such as sodium carbonate,potassium carbonate or a tertiary amine must be present. The reactiontemperature varies from about O-60 C. The preferred procedure is todissolve the bischloroformate in one portion of the organic solvent, theamine hard segment in another portion of the same solvent, combiningthese two portions and mixing the resulting solution with the water-acidacceptor solution. Vigorous agitation is maintained during the reaction.

In solution polymerization, an acid acceptor is used which is soluble inthe solvent employed. Since the solvent is usually one of the organicsolvents mentioned above, the preferred acid acceptors are tertiaryamines.

The reactions employed in preparing the hard segments (see descriptionabove) are generally of five types, (1) production of chloroformates byreacting a diol with phosgene, (2) production of carbamoyl chlorides byreacting a diamine with phosgene, (3) reaction of a chloroformate with adiamine, (4) reaction of a carbamoyl chloride with a diol, or (5)removal of protective groups such as benzyl chloroformates.

The first type reaction is generally carried out by adding the diol ordiamine to liquid phosgene at about 0-30 C. and removing the by-productsat low temperature, i.e., about 50 C. or lower. The second type iscarried out similarly except a tertiary amine is present and thereaction is preferably carried out at 60 to C.

The third type reaction can be carried out substantially as describedabove in the polyether bischloroformate hard segment reaction.

The fourth type reaction of the carbamoyl chlorides and diols is carriedout in an organic solvent in which both reactants and an acid acceptorare soluble, e.g., methylene chloride or chloroform. The acid acceptoris a tertiary amine. A large excess of diol is used and the reactiontemperature is about -150 C.

The fifth type reaction in which the protective groups are removed isknown in the art as hydrogenolysis. The compound containing theprotective groups is contacted with hydrogen in the presence of apalladium catalyst. Preferably, the compound undergoing hydrogenolysisis dissolved in glacial acetic acid. Standard hydrogenation equipmentsuch as a Parr hydrogenation apparatus can be used. The rate of reactionincreases as the pressure of the hydrogen increases. The pressure canvary from about atmospheric to about 400 p.s.i.g. Preferably, thetemperature ranges from 0-60 C.

The invention is further illustrated by the following examples whereinparts and percentages are by weight unless otherwise indicated.Throughout the description of the preparation of intermediate materialsand the examples =phenyl, BDO=1,4-butanediol, Pip=piperazine andPTMEG:polytetramethyleneether glycol of molecular weight 1000.

PREPARATION OF THE INTERMEDIATE MATERIALS 0 Benzyl chloroformate, CH2O C01, XI

The reaction is carried out in a 3 liter flask equipped with agitator,addition funnel, N inlet tube, and reflux condenser which is cooled withcirculating acetone at 70 C. and which is connected in series to adrying tube, bubbler, and ammonia scrubber. Distilled benzyl alcohol(13.5 moles, 1460 g.) is added dropwise with good agitation to refluxingphosgene (20.25 moles, 2001 g.) over a period of 5 hours at 79.5 C. Themixture is allowed to stand overnight in a Dry Ice/acetone bath, afterwhich HCl and excess phosgene are removed by sparging with nitrogen invacuo. The product weighs 2300 g. and contains 20.3% active chloride(theory 20.78%).

BenzyI-l-pipcrazino carboxylutc, C H2O UN N11, XII

Benzylchloroformate (1.18 moles, 170.6 g.) and 4 N NaOH (688 cc.) areadded with agitation at 25 C. to a solution composed of bromophenol blueindicator (0.04%, 60 cc.), piperazine (2 moles, 172.3 g.), concentratedHCl (326 cc.), H (500 cc.), and methanol (1000 cc.) at relative ratessuch that the pH is maintained in the range 3.0-4.5. After addition iscomplete, the methanol is distilled in vacuo, 1000 cc. of H 0 added, andthe pH adjusted to Congo Red end point, and the mixture extracted withbenzene to remove The pH of the aqueous solution is then adjusted to 13with 12.5 N NaOH after which the product is extracted with benzene.After removal of the benzene, 231.8 g. (89.2%) of XII is obtained.Purity by potentiometric titration is 98.2%. A sample of the crudeproduct recrystallized at 70 C. from petroleum ether/diethyl ether hasthe following analysis:

Theory (percent): C, 64.06; H, 6.84; N, 13.59. Found (percent): C,65.25; H, 7.4; N, 12.55.

4-Carb0benzyloxy-I-pipcruzine carbantyl chloride,

A solution of crude benzyl-l-piperazine carboxylate (1.5 moles, 330.5g.), triethylamine (1.5 moles, 151.8 g.), and dry ether (1800 ml.) isadded dropwise with good agitation at 65 C. to 60 C. over a 2-hourperiod to a solution of phosgene (7.5 moles, 742 g.) in dry ether (450ml.). Stirring is continued for /2 hour after addition is complete. Themixture is filtered, the filter cake Washed with dry ether (2000 ml.),and the filtrate evaporated to dryness in vacuo. Crude XIII, a Whitecrystalline solid, is obtained in 386.9 g. (91.2%) yield and melts at58.5-60 C.

AnaIysis.Calcd. for C H ClN O (percent): C, 55.22; H, 5.35; CI, 12.54;N, 9.91. Found (percent): C, 55.3; H, 5.3; CI, 12.6; N, 9.95.

Crude 4-carbobenzyloxy-l-piperazine carbamyl chloride, XIII, (1.827moles, 516.4 g.), 1,4-butanediol (0.6 mole, 54.07 g.) and dry pyridine(50 ml.) are heated at 137 C. for one hour. The reaction mixture iscooled, diluted with Water (100 ml.), and extracted 3 times with 100 ml.portions of methylene chloride. The extract is washed in succession withwater, 10% HCI, 5% sodium carbonate and water. It is then dried oversodium sulfate, filtered, and the solvent removed from filtrate invacuo. Crude XIV, a viscous liquid which slowly crystallizes at roomtemperature, is obtained in 32.9 g. (97.8%) yield.

AmzIysis.Calcd. for C H N O (percent): C, 60.70; H, 7.19; N, 8.33. Found(percent): C, 59.6; H, 7.15; N, 7.88.

ll II II. .poinooN Noownpoootxv active Cl (theory 8.89%), indicating apurity of 95.0%.

i it 0 ml? CH2OCN NCO(CII:)4O( lN Nooolnq xvr A solution of1,4-butanediol bischloroformate (0.5 mole, 107.52 g.) in cold, drymethylene chloride (1612 ml.) is added rapidly with intense agitation toan aqueous solution composed of XII, (1.0 mole, 220.68 g.), sodiumcarbonate (1.0 mole, 106 g.) and H 0 (954 ml.) contained in a l-gal.high-speed mixer. After stirring for 10 min. the methylene chloridephase is separated and washed with H O, the solution dried with sodiumsulfate, and the solvent removed by evaporation. The crude product isrecrystallized from denatured (2B) alcohol. Purified XVI is obtained in286.7 g. (98.4%) yield. It melts at 136.4 137.0 C.

Calcd. for C H N O (percent): C, 61.8; H, 6.57; N, 9.62. Found(percent): C, 61.8; H, 6.5; N(Dumas) 9.6.

A mixture of XVI, (.05 mole, 29.13 g.), glacial acetic acid (167 ml.),and catalyst (5% palladium on activated charcoal, 2.91 g.) is treatedwith hydrogen in a Parr hydrogenation apparatus for 2 hours at aninitial pressure of 54 p.s.i.g. A change in pressure of 6 p.s.i. occursin 11 minutes. The catalyst is removed by filtration and most of theacetic acid by evaporation in vacuo. After dissolving the residue inwater and adjusting the pH to about 13 with KOH solution, the product isextracted with methylene chloride. Evaporation of the methylene chlorideyields 14.5 g. (92% yield) of a white crystalline solid.Recrystallization from heptane produced needles of XVII which melt at9798 C.

Calcd. for C H N O (percent): C, 53.5; H, 8.34; N, 17.82. Found(percent): C, 53.8; H, 8.35; N, 17.7.

A solution of crude XV (94.5% pure, .3437 mole, 122.4 g.) in methylenechloride (CH C1 200 ml.) is mixed in a l-gal. high-speed mixer with asolution of anhydrous piperazine (0.1685 mole, 14.59 g.) in CH CI (776ml.). Anhydrous triethylamine (.378 mole, 38.3 g.) is then added and themixture stirred for 10 minutes. The CH CI solution is washed insuccession twice with H 0 (500 ml.), once with 5% HCl (500 ml.), andonce with H 0 (500 ml.). The solvent is removed by evaporation in vacuoin a rotary evaporator. Crude XVIII is obtained in 118.3 g. (86.6%)yield. Recrystallization from a 3:1 ethanolchloroform mixture produces aWhite crystalline solid melting at 167-l67.5 C.

9 Calcd. for C I- I N O (percent): C, 59.3; H, 6.71; N, 10.37. Found(percent): C, 5.93; H, 6.75; N, 10.2.

A mixture of XVIII, (0.037 mole, 30.0 g.), glacial acetic acid (195ml.), and catalyst palladium on activated charcoal, 3.0 g.) is treatedwith hydrogen in a Parr hydrogenation apparatus for 2 hours at aninitial pressure of 54 p.s.i.g. A change of pressure of 6-6.5 p.s.i. isobtained within 30 minutes. The catalyst is removed by filtration andmost of the acetic acid by evaporation in vacuo. The residue isdissolved in H O, the pH adjusted to above 13 with KOH solution, and theaqueous solution extracted with CI-I C1 Evaporation of the CH Cl yields19.3 g. (96.0% yield) of crude XIX. Recrystalliation from a 1:3heptane-benzene mixture produces 16.24 g. (80.9% yield) of a whitecrystalline solid which melts at 126.5 C. and which is 99.1% pure byamine titration.

Calcd. for C I-I N O (percent): C, 53.12; H, 8.02.; N, 15.49. Found(percent): C, 53.4; H, 7.95; N, 15.25.

Fl! Ii/\lli N-CO(OH2)4O ON NC0OH2, XX L \z a Solid XVII, (0.236 mole,74.29 g.) is added with good agitation to a solution of crude XV (0.473mole, 200.23 g.) in CH Cl (1500 ml.). After /2 minute, a solution ofsodium carbonate (Na CO 0.493 mole), 52.22 g. in H 0 (470 ml.) is addedand the emulsion stirred for 0 EN I minutes. The two phases areseparated, and the CH Cl phase is washed 3 times with H 0 (300 ml.) andthen dried over Na SO Evaporation of the solvent yields 251.3 g.(theory, 246 g.) of crude XX. After recrystalliation from a 1:3.64chloroform-ethanol mixture, the puriified product is obtained in 225.6g. (91.7%) yield. It melts at 180-181" C.

Calcd. for C H N O (percent): C, 57.8; H, 6.79; N, 10.8. Found(percent): C, 57.6; H, 6.8; N(Kj), 10.6.

A mixture of X, (0.03 mole, 31.17 g.), glacial acetic acid (195 ml.),and catalyst (5% palladium on activated charcoal, 3.12 g.) is treatedwith hydrogen in a Parr hydrogenation apparatus for 2 hours at initialtemperature and pressure of 50 C. and 54 p.s.i.g. A total change inpressure of 5 p.s.i. occurs. The catalyst is removed by filtration andmost of the acetic acid by evaporation in vacuo. The residue isdissolved in H O, the pH is adjusted to above 13 with KOH solution, andthe product is extracted with CH Cl After drying the solution oversodium sulfate (Na SO and evaporation of the solvent, crude XXI isobtained in 23.3 g. (101%) yield. Purification by recrystallization froma 1:8.3 H O-tetrahydrofuran mixture produces a 'white powdery solid in20.5 g. (88.8%) yield. Titration for amine indicates 2.52 meq./ g. or apurity of 98.1%.

Calcd. for C H N O (percent): C, 53.0; H, 7.58; N, 14.5. Found(percent): C, 53.1; H, 7.6; N, 14.6.

o o 0 o bCHzOiJN N iiO(CHz) O i JN N i JOGHmXXIII Solid XIX (0.181 mole,"98.4 g.), is added with good agitation to a solution of crude XV (0.369mole, 158.1 g.), in CH Cl (1267 ml.). After /2 minute, a solution of NaCO (0.435 mole, 46.1 g.) in H 0 (415 ml.) is added and the emulsionstirred for 10 minutes. The two phases are separated, and the CH Clphase is washed in succession twice with H 0 (200 ml.), twice with 5%HCl (200 ml.), and twice with H 0 (200 ml.). After drying the CH Clsolution with Na SO the solvent is evaporated, and crude XXII isobtained in 236.7 g. (103%) yield. It is recrystallized from a 1:3chloroform-ethanol mixture to produce a 200 g. (87.3%) yield of whitepowdery solid melting at 184-186 C.

Calcd. for C H N O (percent): C, 56.9; H, 6.84; N, 11.05. Found(percent): C, 56.9; H, 6.8; N, 10.9.

XXII (0.025 mole, 31.68 g.) is dissolved at 50-60 C. in glacial aceticacid cc.), catalyst (5% palladium on activated charcoal) is added, andthe mixture treated with hydrogen in a Parr hydrogenation apparatus for2 hours at an initial temperature and pressure of 55 C. and 55 p.s.i.g.A total change in pressure of 4-4.5 p.s.i. occurs. Catalyst is removedby filtration and most of the acetic acid by evaporation in vacuo. Theresidue is dissolved in H O, the pH adjusted to above 13 with KOHsolution, and the product extracted with CH C1 After drying the solutionwith Na SO and evaporation of the solution to dryness, crude XXIII isobtained in 24.6 g. (98.4%) yield. Purity based on titration for aminecontent is 90.0%. Recrystallization from 1:9 H O-tetrahydrofuran raisespurity to 93.5% Dissolution of the recrystallized product in CH Clfiltration of solution to remove insolubles, and precipitation of theproduct with petroleum ether increases purity to 95.7%.

Final purification is carried out by dissolution of the product inaqueous ethanol, adjustment of pH to above 13, extraction with CH Clwashing of the extract with H 0, and evaporation to dryness. The solidis then dissolved in CH Cland precipitated with petroleum ether. Theproduct thus isolated has a purity of 98.75%.

EXAMPLES 1-3 Preparation of BDO/PTMEG/piperazine polymers withmonodisperse hard segment length distributions All of the polymers inthis series are prepared according to the same general recipe andprocedure described below.

Moles Amount Polytetramethyleneether glycol (1000 1.00

M01. Wt.) bischloroiormate, 6.37 percent 01.

and 2,2-methylene-bis(4-methy1-6- te1t.-butylphenol) (1 part).

XIX-Example 1. XXI-Example 2. XXIII-Example 3.

to the solution of bischloroformate in CH Cl in a 1- quart high-speedmixer. As soon as the solid dissolves, the

1 1 aqueous Na CO solution is added, and the emulsion is stirred for 8minutes. The antioxidant mixture is added to the polymer emulsion andthe polymer is isolated in the mixer by evaporation of the CH Cl withsteam. The polymer is washed free of salts with hot water and dried in avacuum oven at about 75 C. In the case of lowmelting polymers, themolten polymer is redissolved in CH Cl during the washing steps.Characterization data or this series of polymers is shown in thefollowing table.

PROPERTIES OF BDO/lTMEU/PIPERAZINE POYMLERS WITH MONODISPERSE HARDSEGMENT LENGTH DISTRIBUTIONS POLYMER REPEAT SE GMEN'I Inherent viscosityBDO/PTME G- Percent N. 30 C.

,000 pip Example 11 molar ratio Theory Found m-cresol CHOI Analysis byinfrared spectroscopy confirms the presence of the expected urethanelinkages.

Physical properties of the segmented polyurethane are given in the tablewhich follows:

PHYSICAL PROPERTIES OF POLYURETHANES HAVING MONODISPERSE HARD SEGMENTSExample No. 1 2 3 Moles hard segment/kg. polymer 0. 6317 0. 5470 0. 4904Wt. percent, hard segment 37. G 46. 51. G Stress-strain properties:

011 0, p S I 960 I, 480 1, 84 M200, p s 1.... 1, 060 1, 590 2, 000 M p sl 1, 380 1, 990 2, 370 M p s V 1, 710 2, 410 2, 900 M p s 1 2,050 3,0003,610 Mano, p S 1 2, 470 630 5, 250 Mm, p.s.1 3, 410 125 Tensilestrength at break 6, 200 7, 700 9, 200 Elongation at break, p.s. 780 685720 Permanent set, percent 115 173 23G Bashore resilience 61 68 (iHardness, Shore A 95 0G 97 Compression set, 22 hrs./70 C .i 75 58 5;:

When segmented polyurethanes (prepared from the same monomers)containing polydisperse hard segments in which the average value of n is2, 3 or 4 are compared with the polymers of Examples 13, the latter havesubstantially higher modulus and tensile strength and greater Shore Ahardness.

The following ASTM methods were used to obtain the above data: Tensilestrength-D412; modulus-D- 412; elongation at break-D4l2; Bashoreresilience D-1054; hardnessD676 and compression set-D-395.

12 What is claimed is: 1. A segmented polyurethane comprised essentiallyof soft segments and monodisperse hard segments, said polyurethanecorresponding to repeating units of the formula:

wherein G is a bivalent radical obtained by removing the hydroxylhydrogen atoms from a polyalkyleneether glycol having a molecular weightgreater than 400 and a melting point less than 50 C., B is a bivalentradical obtained by removing the hydroxyl hydrogen atoms from a diolhaving a molecular weight less than 400, A is a bivalent radicalobtained by removing a hydrogen atom from each amino group of a primaryor secondary diamine and n is an integer of 2-12.

2. A composition of claim 1 wherein the hard segments of the polymerhave a sufiiciently high melting point that a homopolyrner of said hardsegments has a melting point above about 150 C. at a molecular weightabove about 5000.

3. A composition of claim 1 wherein the diamine and diol having amolecular weight below about 400 are symmetrical compounds.

4. A composition of claim 3 wherein the diamine is a secondary diamine.

5. A composition of claim 1 wherein the segmented polyurethane has aninherent viscosity in m-cresol of at least about 2.0 as measured on asolution of 0.1 gram polymer in 100 milliliters of solvent at 30 C.

6. A polymer of claim 1 wherein the hard segments constitute about 1050%by weight of said polyurethane and n is from 3 to 6.

7. A composition of claim 1 wherein the polyether glycol has a molecularweight of about 600-5000.

8. A composition of claim 7 wherein the diamine is a symmetricalsecondary diamine and the diol of molecular weight below about 400 is asymmetrical diol and n is from 3-6.

9. A composition of claim 8 wherein the diamine is piperazine, the diolis 1,4-butanediol and the polyether glycol is poly(tetramethyleneether)glycol.

10. A composition of claim 9 wherein the segmented polyurethane has aninherent viscosity in m-cresol of at least about 2.0 as measured on asolution of 0.1 gram polymer per 100 milliliter of solution at 30 C. andthe hard segments constitute about 10-50% by weight of the polymer.

0 o 0 II II II -o-c -o 0- References Cited UNITED STATES PATENTS2,929,802 3/1960 Katz 260-775 2,962,470 11/1960 Jung .260 XR 3,044,9877/1962 Schaefgen et a1. 260-75 DONALD E. CZAJA, Primary Examiner M. J.WELSH, Assistant Examiner US. Cl. X.R.

